In timepiece movements, there are several components which pivot about an axis of rotation, such as the pallets, or the balance wheel of an escapement device. Some of these pivoting elements are coupled to a spring, amongst other oscillating elements, such as the balance wheel of the escapement device. In mechanical watches, it is advantageous to have a high-output movement in order to increase the power reserve. The loss of energy due to friction in the bearings of the pivoting parts is one of the greatest sources of energy loss. The quality factor of the parts is also an important consideration for mechanical watches.
In order to reduce these losses, it is known to propose flexible guidance in rotation oscillating about a pivot without bearings, such as described in the patent application EP 2 273 323. This flexible guidance comprises silicon components etched in a silicon wafer in order to produce a monolithic structure comprising a frame, elastic blades and a central attachment body. In order to obtain a sufficiently robust frame and a sufficiently high amplitude of rotation for the oscillator function, a plurality of these monolithic structures are stacked one on the other. One of the disadvantages of this structure is that the manufacturing cost of the three-dimensional monolithic elements is high. Furthermore, the spring blades extending in the radial direction are delicate and do not have an optimum shape for the desired function, i.e. great flexibility in the plane orthogonal to the axis of rotation and great rigidity in the direction of the axis of rotation. In fact, since the blades are etched in a silicon wafer in the direction orthogonal to the surface of the wafer, control of the thickness of the blade is difficult to control with precision, which has a negative influence on performance and in particular well-determined properties of flexibility, robustness and elasticity parameters.